I have several files which are massive in size, but should not be. The files are 20+MB and should be only around 1 MB. When opening with 7-Zip as an archive the file which is unusually large is: 'Workbook.' Also, if you can happen to open the XLS file with excel, and manage to scroll through (past the lag) it comes up with a smile-face. This is not a smile-face that should be in the file. Has anyone heard of such an attack or does anyone know of a fix?

Currently I am running a script which loads the files via ADODB to extract all working data. This will serve as a back-up, however, any sort of fix, or help determining how this happened would be great.
–
TimMar 7 '12 at 21:37

Welcome to Superuser. A little more info will help us help you. What Windows and Office version are you using? Also, have you done any system scans for viruses or damaged/corrupted files (scan-disk)?
–
CharlieRBMar 7 '12 at 23:32

There is not much additional information I can provide. We are on a network of PCs ranging from Windows 2000 to Windows 7. We have Office 2000/2003. The files appear to have been attacked via some sort of virus, which no anti-virus has caught, even in scans of the infected files. However, due to the nature of the "infected" files, I am not sure that they are actually "infected" as much as afflicted. Since the only real harm seems to be an added object made of Excel shapes stacked over and over. Is there perhaps something that could take these shapes out of the file?
–
TimMar 8 '12 at 14:16

PS: When I ask if there is something that could remove the autoshapes from the file, I mean a third-party application. The files, many of them, cannot be opened within excel nor open office.
–
TimMar 8 '12 at 14:30

Is it possible that a user could have opened these files in a later version of Office? If that is done, and the file is saved as an xlsx format, they realize that was wrong and rename the extension to xls, the format will be un-recognizable and if it does open at all you will see a mess.
–
datatooMar 13 '12 at 2:25